General Four Layer Pcb Design; Phase1: Layer Assignment; Figure 17. The Two Layers Of The Eunistone Usb Dongle - Panasonic eUniStone Application Note Design Manual



Figure 17. The two layers of the eUniStone USB Dongle.

Observe that there is no copper in any layer under the antenna.
7.2

General four layer PCB design

This chapter describes a general four layer PCB design aimed for more complex cards which have host
processors connected to multiple device and possible also clock signals, address and data buses.
Layout design can be divided into the following phases:

Phase 1: layers assignment.

Phase 2: components placement.

Phase 3: routing.
7.2.1

Phase1: Layer Assignment

A correct assignment of the layers may avoid any RF issues. And can make the routing a lot easier.
Figure 18
shows the layers of a general four layer design. In this case, because the number of
connections is very small, no special care is required in this phase:

The top layer is reserved for components' placement.

Mid layer 1 is used as RF ground and to route some traces

Mid layer 2 is used for power planes.

Bottom layer is used for general grounding and to route the rest of the traces
Application Note
Design Guide
46
PAN1322
Revision 1.2, 2013-12-18